device that provides the necessary force to position a damper 

1. reducing the amplitude of vibrations by dissipating the corresponding mechanical energy to some suitable absorbing sink.

2. progressive diminution with time of certain quantities charac­terizing a phenomenon.

measure of permeability. At one darcy, a material will pass a fluid of one centipoise vis­cosity through a section of one square centimetre at a rate of one cubic centimetre per second, with a drop in pressure of one standard atmo­sphere.

1. general term used to denote any or all facts, numbers, letters, and symbols that refer to or describe an object, idea, condition, situation, or other factors.

2. representations such as characters or analog quantities to which meaning might be assigned.

1. to operate equipment prior to use to detect and replace parts that are defective or expected to fail, and to correct error in fabri­cation or assembly.

unit used in acoustics for expressing the relation between two amounts of airborne power. By definition, the dif­ference in decibels between two powers P₁ and P₂, P₂ being the larger is: db difference = 10 log (to the base 10) P₂/P₁ 

angle of the sun above or below the equato­rial plane. It is plus if north of the plane and minus if south.

process of chemical change; break­ing up of structures; spoilage. Compare deterioration 

1. quantity by which a variable is decreased.